One thing I've been curious about and I keep forgetting to ask...

My car, a '79 300TD, smokes like crazy from the exhaust pipe.  I pull up
to a light, and a cloud envelopes the car to pull up beside me.  The
inside of the car gets the smell of burnt fuel too, I'm not sure if I'd
say "exhaust" or not, though.  It's less noxious on veggie oil, but the
same phenomenon occurs regardless of choice of fuel (although when I did
Marvel in a tank the problem disappeared for about 50 miles!).

My partner's car, an '85 300D, doesn't noticeably smoke at all and
doesn't stink inside the passenger compartment or anything.  She doesn't
like riding in my car because of the difference.

So, I know nothing of emissions controls except that I know the vacuum
diagrams seemed to change every year and it was emissions "stuff" that
was notably different.  Ultimately, my question is about whether or not
I have EGR equipment on my car, could it be fouled or otherwise in need
of replacement, how do I find it, and how do I test it?  I'm hoping that
something like this would be an "easy" fix for me.

FWIW, I've had the car at an exhaust shop and they replaced "cat-back"
but said there were no leaks in the system once the rust in the "back"
was taken care of, and in my looking I don't see any "smoke" in the
engine compartment but it definitely smells like something that it
shouldn't smell like (and this smell should not be going into the
passenger compartment!).

thanks,
-tom!

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